Atmospheric parameters and rotational velocities for a sample of Galactic B‐type supergiants
Atmospheric parameters and rotational velocities for a sample of Galactic B‐type supergiants
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DOI：
10.1111/j.1365-2966.2010.16392.x
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发表时间：
2010-01
影响因子：
4.8
通讯作者：
M. Fraser;P. Dufton;I. Hunter;R. D. O. Physics;Astronomy;Queen's University of Belfast
中科院分区：
文献类型：
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作者：
M. Fraser;P. Dufton;I. Hunter;R. D. O. Physics;Astronomy;Queen's University of Belfast
分析了57颗银河系B型超巨星的高分辨光谱，确定了它们的自转速度和宏观湍流速度。此外，他们的大气参数（有效温度，表面重力和微湍流速度）和表面氮丰度已估计使用非本地热力学平衡网格模型大气。预测的旋转速度已经与恒星演化模型的预测进行了比较，并在一般良好的协议被发现。然而，对于少数目标，他们的观测到的旋转速度显着大于预测，虽然他们的氮丰度是一致的，其余的样品。我们的结论是，二进制可能发挥了作用，在产生大的旋转速度。氮丰度和目前预计的旋转速度之间没有相关性。然而，相关性被发现与我们的超巨星样本的主序列前体的推断投影旋转速度。这种相关性再次与包含旋转混合的单颗星星演化模型的预测一致。的宏观湍流和微观湍流速度场的起源进行了讨论，我们的结果支持以前的理论研究，前者的亚光球对流和后者的非径向重力模式振荡。此外，我们还试图在我们最快速旋转的目标中识别差异旋转。
High-resolution optical spectra of 57 Galactic B-type supergiant stars have been analysed to determine their rotational and macroturbulent velocities. In addition, their atmospheric parameters (effective temperature, surface gravity and microturbulent velocity) and surface nitrogen abundances have been estimated using a non-local thermodynamic equilibrium grid of model atmospheres. Comparisons of the projected rotational velocities have been made with the predictions of stellar evolutionary models and in general good agreement was found. However, for a small number of targets, their observed rotational velocities were significantly larger than predicted, although their nitrogen abundances were consistent with the rest of the sample. We conclude that binarity may have played a role in generating their large rotational velocities. No correlation was found between nitrogen abundances and the current projected rotational velocities. However, a correlation was found with the inferred projected rotational velocities of the main-sequence precursors of our supergiant sample. This correlation is again in agreement with the predictions of single star evolutionary models that incorporate rotational mixing. The origin of the macroturbulence and microturbulent velocity fields is discussed and our results support previous theoretical studies that link the former to subphotospheric convection and the latter to non-radial gravity mode oscillations. In addition, we have attempted to identify differential rotation in our most rapidly rotating targets.